Machinable alloys

ABSTRACT

A freely machinable alloy comprising, as expressed in percent by weight: Nickel 25%- 32%; Cobalt 6.5%-27%; Selenium 0.1%- 0.4%; Manganese 0.5%- 1.5%; Iron

United States Patent Majesko Mar. 7, 1972 [54] MACHINABLE ALLOYS [72] Inventor: George A. Majesko, Glen Ridge, NJ.

[73] Assignee: Wilber B. Driver Company [22] Filed: 'Nov. 3, 1969 [21] Appl. No.: 873,508

[52] US. Cl ..75/123 AA, 75/123 K, 75/123 N [51] Int. Cl. ..C22c 39/10, C22c 39/26, C22c 39/54 [58] Field of Search ..75/123 AA, 123 K, 123 N, 126 M,

[56] References Cited UNITED STATES PATENTS 1,987,714 1/1935 Scott ..75/123 K X 2,960,402 11/1960 Smithi... ..75/ 123 K X 2,062,335 12/1936 Scott ..75/123 K 2,941,882 6/1960 Franklin et al.. .75/123 K 2,009,713 7/1935 Palmer 75/123 AA 2,553,330 5/1951 Post 75/123 AA 2,315,294 3/1943 Stewart et a1. ...75/123 K 2,491,787 12/1949 Went ..75/123 K 2,009,715 7/1935 Palmer ..75/123 AA 3,169,857. 2/1965 Rathke et al ..75/123 AA FOREIGN PATENTS OR APPLlCATlONS 654,294 6/1951 Great Britain ..75/128 P Primary Examiner--L. Dewayne Rutledge Assistant Examiner-J. E. Legru AnorneyNorman J. O'Malley and Theodore C. Jay, Jr.

[5 7] ABSTRACT A freely machinable alloy comprising, as expressed in percent by weight:

Nickel 25%-32%; Cobalt 6.5%27%: Selenium 0. 1% 0.4%; Manganese 0.5%1.5%; Iron Balance 4 Claims, No Drawings MACHINABLE ALLOYS SUMMARY OF THE INVENTION A well-known group of alloys of the nickel-cobalt-iron type are used in forming seals between metals and glass or metals and ceramics as well as in other applications wherein the thermal coefficients of expansion and other properties are critical. Alloys in this group are often referred to as expansion alloys.

Many expansion alloys are characterized by the undesirable property of poor machinability. As a result, tools used in shaping such alloys wear much too rapidly, even when the machining is carried out at relatively low speeds and feed rates.

I have discovered that the addition of selenium in amounts falling within the range 0.1 percent to 0.4 percent (be weight) coupled with the simultaneous addition of manganese in amounts falling within the range 0.5 percent to 1.5 percent to a nickel-cobalt-iron alloy comprising 25 percent to 32 percent nickel, 6.5 percent to 27 percent cobalt, balance iron, results in alloys with sharply enhanced machinability and, at the same time, with otherwise substantially unchanged physical and mechanical properties. As a result, excessive tool wear no longer takes place.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS A first plurality of alloys were fabricated with compositions falling within the ranges set below:

Nickel 25%-29%; Cobalt use-27%: Selenium 0. Via-0.4%; Manganese 0.5%-l.5%;

Minor elements (silicon, carbon, etc.) 1% Balance lron A second plurality of alloys without selenium and with a manganese content of less than 0.5 percent but otherwise of like composition to the first plurality were fabricated in the same manner.

Both sets of alloys were tested for machinability in accordance with the different r.p.m. and feed rates set forth in Table 1 below:

For constant depth of cut (0.025 inches) and feed rate (0.0042 inches/rev.) the selenium-containing alloys could be turned on a lathe at 241 surface feet per minute with no undesirable effects. The workpiece remained cool. The selenium free alloys became very hot at 72 surface feet per minute and the machining lubricant began to smoke at 93 surface feet per minute causing a sharp deterioration of the surface finish.

At a constant r.p.m. of 1,600 and a depth of cut of 0.025 inches, the selenium containing alloys could be fed in a trouble-free manner at rates ranging from 0.0042 to 0.0384 inches/rev. Under the same conditions the selenium-free alloys ruined the tool when the feed rate was increased beyond 0.0060 inches/rev.

A third plurality of alloys were fabricated with compositions falling within the ranges set forth below:

Nickel Nil-30%; Cobalt 1611-1 8%; Selenium ONE-0.4%; Manganese 0.5%l.5%;

Minor elements (silicon, carbon, etc.) l% Balance Iron A fourth plurality of alloys without selenium and with a manganese content of less than 0.5 percent, but otherwise of like composition to the first plurality were fabricated in the same manner.

The machinability tests previously described were repeated with essentially the same results.

A fifth plurality of alloys were fabricated with compositions falling within the ranges set forth below:

Nickel 30.75-31.75% Cobalt 6.5-8.5% Selenium 0. l-0.4% Manganese 0.5-1.5%

Minor elements (silicon, carbon, etc.) l% Balance lron A sixth plurality of alloys without selenium and with a manganese content of less than 0.5 percent, but otherwise of like composition to the fifth plurality were fabricated in the same manner.

The machinability tests previously described were repeated with essentially the same results.

1 found that when the selenium content was reduced below about 1 percent and the manganese content was reduced simultaneously below 0.5 percent, the machinability characteristics were not substantially improved as compared to known alloys. When the selenium content was increased about 0.4 percent and the manganese content was increased simultaneously above 1.5 percent, the machinability characteristics were not degraded, but the thermal expansion properties of the alloys began to vary beyond the ranges specified and required. As long as the selenium and manganese additions are maintained within the ranges set forth herein, any increase of selenium content must be accompanied by an increase (not necessarily a proportional increase) in the manganese content to maintain forgeability.

What is claimed is:

1. A freely machinable alloy consisting essentially of, as expressed in percent by weight:

Nickel 25-32% Cobalt 6.5-27% Selenium 0.1-0.4% Manganese 0.5-1.5% and Iron Balance,

wherein said said alloy an increase in selenium content within said weight range is accompanied by an increase in manganese content within said weight range.

2. An alloy as set forth in claim 1 comprising 25 percent to 29 percent nickel and 23 percent to 27 percent cobalt.

3. An alloy as set forth in claim 1 comprising 28 percent to 30 percent nickel and 16 percent to 18 percent cobalt.

4. An alloy as set forth in claim 1 comprising 30.75 percent to 31.75 percent nickel and 6.5 percent to 8.5 percent cobalt.

r a s a 

2. An alloy as set forth in claim 1 comprising 25 percent to 29 percent nickel and 23 percent to 27 percent cobalt.
 3. An alloy as set forth in claim 1 comprising 28 percent to 30 percent nickel and 16 percent to 18 percent cobalt.
 4. An alloy as set forth in claim 1 comprising 30.75 percent to 31.75 percent nickel and 6.5 percent to 8.5 percent cobalt. 